In the 3rd Generation Partnership Project (3GPP), a radio access scheme (Evolved Universal Terrestrial Radio Access (EUTRA)) and a radio access network (Evolved Universal Terrestrial Radio Access Network (EUTRAN)) for cellular mobile communication have been considered. EUTRA and EUTRAN are also referred to as Long-Term Evolution (LTE). In LTE, a base station apparatus is also referred to as an evolved NodeB (eNodeB) and a terminal device is also referred to as a User Equipment (UE). LTE is a cellular communication system in which an area is divided in a cellular pattern into multiple cells, each being served by a base station apparatus. A single base station apparatus may manage multiple cells.
In 3GPP, Proximity Services (ProSe) have been considered. ProSe includes ProSe discovery and ProSe communication. The ProSe discovery is a process that, using EUTRA, specifies that a terminal device is in proximity to a different terminal device. The ProSe communication is communication between two terminal devices that are in proximity to each other using a EUTRAN communication path that is established between the two terminals. For example, the communication path may be established directly between the terminal devices.
The ProSe discovery and the ProSe communication are also referred to as D2D discovery and D2D communication, respectively. The D2D discovery and the D2D communication are collectively also referred to as D2D.
In NPL 1, it is disclosed that a subset of resource blocks is reserved for the D2D, that a network configures a set of D2D resources, and that the terminal device is allowed to transmit a D2D signal using the configured resources.